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2 years ago

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A group of graduate students, bored during a cloudy night at the observatory, begin to make bets about the time different stars

will take to evolve. If they have a cluster of stars which were all born at roughly the same time, and want to know which star will become a red giant first, which of the following stars should they bet on:__________.
a) a star of about 8% the mass of our Sun
b) a star that would type on the main sequence star
c) a star of about the same mass as our Sun
d) you can't fool me, all stars reach the red giant stage in roughly the same number of years
e) a star of about 1/2 the mass of our Sun

1 answer:

Marina CMI [18]2 years ago

8 0

Answer:

yes

Explanation:

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Water evaporates off lakes. Winds blow across the planet. Where does the energy come from for these and other weather processes?

Otrada [13]

Answer:

B. Solar energy

Explanation:

The water cycle is driven primarily by the energy from the sun. This solar energy drives the cycle by evaporating water from the oceans, lakes, rivers, and even the soil. Other water moves from plants to the atmosphere through the process of transpiration.

8 0

2 years ago

Read 2 more answers

Large capacitors can hold a potentially dangerous charge long after a circuit has been turned off, so it is important to make su

KengaRu [80]

Answer:

93.3x10^-3s

Explanation:

If

Resistance = 1.8 kΩ

Current = 50 mA

Capacitor = 120 μF

Voltage = 140 V

to calculate the discharge current

Applying the formula of discharge current

io=vo/R

io= 140/ 1.8x 10³

= 0.078A

to calculate the time

Applying the formula of current

io= vo/R e-t/RC

50= 140/1800e-t/RC

0.649= e-t/RC

-t/RC= ln( 0.649)

t = 0.432x 120x10^-6x 1800

t=93.3 x 10^-3seconds

8 0

2 years ago

Ball 1 travels with a momentum of 48.0 kg-m/s east and strikes Ball 2, which is initially at rest.. Ball 1 separates at an angle

vladimir1956 [14]

Answer:

Momentum of 2nd ball is

$P = 31.6 kg m/s$

direction is given as

$\theta = -37.66 degree$

Explanation:

As we know that there is no external force on the system of balls so momentum before and after collision will be conserved

So we have

$P_i = 48 \hat i + 0$

now after collision momentum of two balls is must be same as initial

so we have

$P_i = P_f$

$48\hat i = (30 cos40 \hat i + 30 sin40\hat j) + (P_{2x}\hat i + P_{2y}\hat j)$

so we have

$48 = 23 + P_{2x}$

$P_{2x} = 25 kg m/s$

for other component we have

$0 = 19.3 + P_{2y}$

$P_{2y} = -19.3 kg m/s$

Momentum of 2nd ball is given as

$P = \sqrt{P_2x}^2 + P_{2y}^2}$

$P = 31.6 kg m/s$

direction is given as

$tan\theta = \frac{P_{2y}}{P_{2x}}$

$tan\theta = \frac{-19.3}{25}$

$\theta = -37.66 degree$

5 0

2 years ago

A world-class sprinter running a 100 m dash was clocked at 5.4 m/s 1.0 s after starting running and at 9.8 m/s 1.5 s later. In w

cupoosta [38]

Answer:

<em>The output power is greater in the interval from 1.0 s to 2.5 s</em>

Explanation:

<u>Physical Power </u>

It measures the amount of work W an object does in certain time t. The formula needed to compute power is

$\displaystyle P=\frac{W}{t}$

Work can be computed in several ways since we are given the motion conditions, we'll use this formula, for F= applied force, x=distance parallel to F

$W=F.x$

The second Newton's law gives us the net force as

$F=m.a$

being m the mass of the object and a the acceleration it has for a given period of time. In our problem, we have two different behaviors for each interval and we must calculate this force since the acceleration is changing. Let's calculate the acceleration in the first interval. We can use the formula for the final speed vf knowing the initial speed vo (which is 0 because the sprinter starts from rest), the acceleration a, and the time t:

$v_f=v_o+at$

$v_f=at$

Solving for a

$\displaystyle a=\frac{v_f}{t}={5.4}{1}$

$a=5.4\ m/s^2$

The distance traveled in the interval is given by

$\displaystyle x=v_o.t+\frac{a.t^2}{2}$

Since vo=0

$\displaystyle x=\frac{a.t^2}{2}=\frac{5.4(1)^2}{2}$

$x=2.7\ m$

The force is given by

$F=m.a$

We don't know the value of m, so the force is

$F=2.7m$

Computing the work done by the sprinter

$W=F.x=2.7m(5.4)$

$W=14.58m$

The power is finally computed

$\displaystyle P=\frac{W}{t}=\frac{14.58m}{1}$

$P=14.58m$

During the second interval, from t=1 sec to 1.5 sec, the speed changes from 5.4 m/s to 9.8 m/s. This allows us to compute the second acceleration

$\displaystyle a=\frac{v_f-v_o}{t}=\frac{9.8-5.4}{0.5}$

$a=8.8\ m/s^2$

The distance is

$\displaystyle x=(5.4).(0.5)+\frac{8.8(0.5)^2}{2}$

$x=3.8\ m$

The net force is

$F=m(8.8)=8.8m$

The work done by the sprinter is now computed as

$W=8.8m(3.8)=33.44m$

At last, the output power is

$\displaystyle P=\frac{33.44m}{0.5}=66.88m$

By comparing both results, and being m the same for both parts, we conclude the output power is greater in the interval from 1.0 s to 2.5 s

6 0

2 years ago

What unit is used to measure energy when calculating specific heat capacity? Give the abbreviation, not the full name.

Svet_ta [14]

Energy is in Joules ( J )
specific heat capacity is in ( Joules per Kilogram per degree Celsius) ( J/kg C )

3 0

2 years ago